1. Field of the Invention
The present invention relates to a holder blade for clamping in place a metal cutting insert of a tool such as, for example, a cut-off or parting tool.
2. Description of Prior Art
It is known to provide a holder blade which holds a metal cutting insert in place while performing metal cutting operations such as cutting off and grooving. Such a holder blade is typically a relatively narrow insert support which is held in place by being clamped in dove-tailed holders attached to the machine tool. Known prior art holder blades include an aperture into which the cutting insert is inserted such that the insert cutting edge extends beyond the holder blade for cutting a workpiece, the aperture having substantially planar upper and rear surfaces, and a lower surface having a generally V-shaped design, which conforms to mating surfaces of the insert. An example of one known holder blade is described in U.S. Pat. No. 4,357,123 to Zweekly which is incorporated herein by reference. In such a device, after extended use the force exerted by the opposing surfaces or jaws of the holder blade which engage the cutting insert to hold it in place tends to decrease. The result is that the insert will have a tendency to slide or otherwise move relative to the opposing surfaces or jaws and this will tend to adversely affect the accuracy of the cutting operation. Such a sloppy fit is undesirable In an extreme situation the holder blade may actually break, typically at a position located at a narrow land area between the aperture into which the insert has been inserted and an inner terminus of a slit which is provided in the holder blade to facilitate the camming action which holds the insert in place. Whether the insert moves relative to the holder blade or the holder blade actually breaks, it will be necessary to shut down the machine and replace the holder blade.
It is an object of the present invention to provide an improved holder blade.
It is another object of the present invention to provide such a holder blade wherein the tendency of the insert held by the holder blade to move relative thereto after extended use will be substantially reduced.
Yet another object of the present invention is to provide such a holder blade which will have less of a tendency to break after extended use.